Hostile environment

BE-SS29 Advanced Maintenance advisory surveillance system for equipment operating in hostile environments fAMASS) Mr. V. Mendes Martins EDP S.A... 

Reactions represent the dynamic aspect of chemistry, the interconversion of chemical compounds. Chemical reactions produce the compounds that are sold by industry and that play a big role in maintaining the standard of living of our society they transform the food that we take up in our body into energy and into other compounds and they provide the energy for surviving in a hostile environment and the energy for a large part of our transportation systems. 

Host-guest chemistry Hostile environments Hot briquetted iron... 

Tips of platinum, platinum—nickel alloy, or iridium can be resistance-welded to spark-plug electrodes for improved reHabiHty and increased lifetime. These electrodes are exposed to extremely hostile environments involving spark erosion, high temperature corrosion, thermal shock, and thermal fatigue. 

PPS fiber has excellent chemical resistance. Only strong oxidising agents cause degradation. As expected from inherent resia properties, PPS fiber is flame-resistant and has an autoignition temperature of 590°C as determined ia tests at the Textile Research Institute. PPS fiber is an excellent electrical iasulator it finds application ia hostile environments such as filter bags for filtration of flue gas from coal-fired furnaces, filter media for gas and liquid filtration, electrolysis membranes, protective clothing, and composites. 

Electrochemical Microsensors. The most successful chemical microsensor in use as of the mid-1990s is the oxygen sensor found in the exhaust system of almost all modem automobiles (see Exhaust control, automotive). It is an electrochemical sensor that uses a soHd electrolyte, often doped Zr02, as an oxygen ion conductor. The sensor exemplifies many of the properties considered desirable for all chemical microsensors. It works in a process-control situation and has very fast (- 100 ms) response time for feedback control. It is relatively inexpensive because it is designed specifically for one task and is mass-produced. It is relatively immune to other chemical species found in exhaust that could act as interferants. It performs in a very hostile environment and is reHable over a long period of time (36). 

Salt preserves foods by providing a hostile environment for certain microorganisms. Within foods, salt brine dehydrates bacterial cells, alters osmotic pressure, and inhibits bacterial growth and subsequent spoilage. Dry salt and salt brine are used in several types of curing processes. Pickles are preserved in strong brine before final processing. 

Optical. Besides the gem quaHties dependent on optical properties, diamond is very useful as a light-transmitting window for lasers and for simple windows for monitoring chemical processes in corrosive and otherwise hostile environments. 

After insertion of an lUD, polymorphonuclear leukocytes and macrophages accumulate in the uterine cavity. These cells appear to phagocytize sperm and Hberate a blastotoxic toxin (92,93). Intrauterine devices also may create a hostile environment, perhaps because antibodies are produced that interfere with implantation of the fertilized ovum (93). 

Corrosion. Copper and selected copper aHoys perform admirably in many hostile environments. Copper aHoys with the appropriate corrosion resistance characteristics are recommended for atmospheric exposure (architectural and builder s hardware), for use in fresh water supply (plumbing lines and fittings), in marine appHcations (desalination equipment and biofouling avoidance), for industrial and chemical plant equipment (heat exchangers and condensers), and for electrical/electronic appHcations (coimectors and semiconductor package lead-frames) (30) (see Packaging). 

Fluoiocaibon elastomeis aie synthetic, noncrystaUine polymers that exhibit elastomeric properties when cross-linked. They are designed for demanding service appHcations in hostile environments characterized by broad temperature ranges and/or contact with chemicals, oils, or fuels. 

These benefits directly translate into lower costs and improved operating efficiency for rotating machinery. Lubrication is unnecessary. The bearing is operable in hostile environments and, in many cases, can operate in the process fluid at high pressures and temperatures. Experience shows that total consumption of frictional power is drastically reduced. 

Experience with uncoated IN-738 blades in this very hostile environment indicates about 25,000 hours blade life can be attained. The coated blade life, based on this interim evaluation, should add an additional 20,000 hours of life. 

For many reasons, it may be ineonvenient to take the speetrum analyzer to the field eaeh time an analysis is to be made. Often, several maehines are to be analyzed at various loeations. Also, a hostile environment may exist at the test site, whieh might result in damage to the analyzer. A way of over-eoming these problems is offered by data taping. With a tape, a permanent reeord is made. Sinee eaeh ehannel of the tape offers a plaee for data to be stored, this reeord may be a eondensation of several inputs either from different transdueers or from the same transdueer at various loeations. A eontinuous tape monitor is very benefieial. In the event of maehine failure, an analysis of the playbaek will help diagnose the problem. 

Condensation of high-boiling-point components in the line between sample head and sensor Hostile environment... 

Special quality steels - A vast range of special quality steels is made in electric arc furnaces by adding other metals to form steel alloys. The most commonly known of these is stainless steel, which has chromium and nickel added to form a corrosion-resistant steel. There are very many others however the very hard steels used to make machine tools, the steels specially formulated to make them suitable for engineering, steels developed to survive for decades the hostile environment of nuclear reactors, light but strong steels used in aerospace, extra tough steels for armor plating - to name but a few. 

The 3-lactam antibiotics are cell-wall inhibitors toward susceptible bacteria. To survive in a hostile environment with ionic strengths often quite different from the interior of the cell, bacteria have evolved a rigid, quite complex cell wall. 

As drilling technology moved the pursuit of hydrocarbon resources into higher-cost offshore and hostile environments, intentionally deviated boreholes required information such as azimuth and inclination that could not be derived by surface instruments. Survey instruments, either lowered on a sand line or dropped into the drill pipe for later retrieval, to some degree satisfied the requirements but consumed expensive rig time and sometimes produced questionable results. 

There are various theories on how passive films are formed however, there are two commonly accepted theories. One theory is called the oxide film theory and states that the passive film is a diffusion-barrier layer of reaction products (i.e., metal oxides or other compounds). The barriers separate the metal from the hostile environment and thereby slow the rate of reaction. Another theory is the adsorption theory of passivity. This states that the film is simply adsorbed gas that forms a barrier to diffusion of metal ions from the substrata. 

Access for air into the boiler house must be considered. Air for combustion will be drawn in through purpose-made louvers and care should be taken that this air does not create a hostile environment to personnel in the building. Also, passage of air across cold water pipes should be avoided, as in cold weather this may aggravate freezing in the pipes. 

Designing the membrane structure for a reverse osmosis plant is a difficult project, particularly in view of the fact that in addition to the pressure exposure, the presence of strong concentrations of dissolved minerals is a hostile environment for plastics. 

The rapid cooling of certain plastic products can result in frozen in stresses and strains (particularly with injection molding). The stresses may decay with time in a viscoelastic manner. However, they will act like any other sustained stress to aggravate cracking or crazing in the presence of aggressive media and hostile environments like UV radiation. 

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